Male Reproduction Flashcards
1
Q
Reproduction requires fusion of ________ from a man and a woman
A
Gametes
2
Q
gametes are produced in (primary/secondary) sex organs
A
Primary
3
Q
What are the male accessory structurs?
A
Penis
Scrotum
Vas deferens
Epididymis
Accessory glands
4
Q
What are the male secondary sexual characteristics?
A
Facial/body hair
Larger muscle mass
Masculine jaw
Height
(Ornamental things that kind of just demonstrate the “fitness” of a person)
5
Q
What are the 2 kinds of cells in the seminiferous tubules?
A
Germ cells (spermatogonia)
Sertoli cells
6
Q
Where does spermatogenesis happen?
A
Seminiferous tubules
7
Q
What kind of cells are in the connective tissue of the testes?
A
Leydig cells
8
Q
The testes are 80%_______ and 20%___________, by weight
A
80% seminiferous tubules
20% connective tissue
9
Q
What do germ cells do?
A
They are sperm precursors
10
Q
What do Sertoli cells do?
A
They are “support cells” to developing sperm. Make:
Antimullerian hormone
Androgen binding protein
Inhibin
11
Q
What do Leydig cells (in the connective tissue) do?
A
Secrete testosterone
12
Q
What hormone mediates spermatogenesis
A
Testosterone
13
Q
How long does spermatogenesis take
A
~74 days
14
Q
spermatogonia are (diploid/haploid)
Spermatozoa aka sperm are (diploid/haploid)
A
Diploid
Haploid
15
Q
What are the 3 stages of spermatogenesis?
A
- Mitosis (proliferation)
- Meiosis (2 divisions)
- Spermiogenesis (packaging)
16
Q
What happens during mitosis?
A
Each germ cell divides twice to create 4 diploid primary spermatocytes (DOUBLE stranded DNA)
17
Q
What happens during meiosis?
A
Undifferentiated diploid germ cells are converted into haploid spermatocytes (2 division to create 16 spermatids with SINGLE strands of one chromosome)
18
Q
Each spermatogonia can turn into _____ sperm
A
16
19
Q
At what age do spermatogonia undergo mitotic divisions
A
Puberty
20
Q
After a spermatogonia enters its first meiotic division, what is it called?
A
Primary spermatocyte.
-> becomes 2 secondary spermatocytes -> each one enters second meiosis-> 2 spermatids
21
Q
Do the spermatids completely separate from each other?
A
No, the 4 spermatids that came from a single primary speratocyte stay stuck together in a syncytium until its time to completely mature
22
Q
What is the purpose of the syncitium?
A
Ensures that the haploid cells that contains either an X or Y chromosome have access to all the gene products available in a complete diploid genome**
23
Q
What protects the developing, genetically-variant sperm from the man’s immune system?
A
Tight junctions between the Sertoli cells. The “blood-testes” barrier.
24
Q
Does every spermatogonia enter meiosis 1?
A
No, some stay and maintain the germ line
25
What holds the spermatids together in the syncititum?
Cytoplasmic bridges join them together.
| Allows XY sperm to transport necessary gene products to XX sperm...allows full access to the complete gene product
26
How do the developing sperm get nutrients?
Gap junctions between the spermatocytes and Sertoli cells.
27
What are the duties of Sertoli cells
1. Protect sperm and provide nourishment
2. Absorb excess cytoplasm and waste from delveoping sperm
3. Secrete seminiferous tubule fluid
4. Produce androgen binding protein
5. Secrete anti-mullerian factor during development
6. Release inhibin
28
What is the purpose of seminiferous tubule fluid?
Flushes sperm to epididymis
29
Is there more testosterone in the lumen of seminiferous tubules or in the blood?
100x more testosterone in the lumen primarily due to the ABP produced by Sertoli cells, that sequesters Testosterone.
30
Where does inhibin come from
Sertoli cells
31
What causes the Sertoli cells to release inhibin
T and FSH
32
What does anti-mullerian factor do?
Suppresses the development of the female reproductive tract
33
What is this:
| “Process by which spermatids mature into spermatozoa”
Spermiogenesis
(Turning it from a round little cell into the little swimmers we all know and hate)
<>~~~~
34
What happens to the head of the sperm during spermiogenesis
It elongates and most of the cytoplasm is lost
Nucleus remodels: chromatin condenses
Lysosomes aggregate to from the acrosome (pack of digestive enzymes)
35
What is in the mid piece of the sperm
A bunch of mitochondria
36
What is in the tail of the sperm
Microtubules that move
37
What is this:
| “Process by which mature sperm are extruded from Sertoli cells into the lumen of the seminiferous tubules”
Spermiation
38
What propels the mature sperm from the seminiferous tubules into the Rete testes and epipdidymis
Contraction of myoepithelial muscles and pressure of fluid from the Sertoli cells
(THEY DON’T SWIM)
39
What happens in the epididymis?
Sperm storage area where they mature even more
40
Can sperm swim when they’re in the epididymis
NO
41
Is the rate of sperm production influenced by hormones?
No it is CONSTANT
42
What allows the continuous production of sperm along the length of the seminiferous tubule?
“Spermatogenic Wave”
43
What is the spermatogenic wave?
Its due to different waves of spermatogensis occurring simultaneously along the length of the tubule. I.e., you wouldn’t find all sperm in all stages of development in a single cross section, they would all be in about the same stage
44
Spermatogenesis requires temperatures (warmer/cooler) than body temp
Cooler. 1-2 degrees cooler
45
Why do developing sperm need to be kept cooler?
Prevents lysosomal destruction
46
What are the 3 ways that sperm are kept cooler
Air around scrotum
Contraction/relaxation of rugae muscles
Venous blood flow (countercurrent heat exchange)
47
What is the most widespread environmental factor that produces low sperm counts
Interference with the ability of scrotum to cool the testes: tight clothing, sitting too long, hot tubs
48
If you have cryptorchidism, can you produce viable sperm?
No. (I think because its too warm?)
49
What does FSH do?
Sensitizes Sertoli cells to testosterone
Promotes Inhibin and ABP secretion from Sertoli cells
50
Which cells in the testes are targeted by FSH
Sertoli cells
51
What does luteinizing hormone LH do?
Stimulates cholesterol desmolase within Leydig cells to produce testosterone ** (Rate limiting step)
52
What cells in the testes are targeted by LH
| /
Leydig cells
53
How do inhibin and testosterone regulate the release of FSH and LH
Inhibin: only FSH (selective inhibition)
Testosterone: LH and FSH (negative feedback)
***
54
What are the effects of testosterone? (There are a lot just read this card)
1. Embryonic/fetal development- masculinize reproductive tract and external genitals. Promote descent of tests into scrotium
2. Sex-specific tissue after birth- maturation of reproductive system at puberty. Spermatogenesis. Maintain reproductive tract throughout life
3. Reproduction-increase sex drive. Control secretion of gonadotropins (LH and FSH)
4. Secondary sex characteristics- male pattern hair growth. Deep voice. Muscle growth and male adiposity
5. Non reproduction- muscle mass, bone density, closes epiphyseal plates, aggressive behavior, brain development in pre-optic area, hippocampus and amygdala
55
How does testosterone close the epiphsyeal plates
Via aromatase conversion to estrogen
56
Testosterone can be peripherally converted to what 2 things?
dihydrotestosterone (DHT)
estradiol (E2)
57
What enzyme makes DHT?
5α-reductase
58
What enzyme makes estradiol
Aromatase
59
How is testosterone concentrated within the seminiferous tubules/
By binding to ABP
60
How does testosterone travel through the circulation
Bound to sex hormone binding globulin (SHBG)
61
What is the rate limiting step of testosterone synthesis?
The conversion of cholesterol to pregnenolone by cholesterol desmolase
(REGULATED BY LH- increases the affinity of cholesterol desmolase to cholesterol)
62
Does testosterone always need to be converted to DHT or E2?
No, it has some directbeffects that dont require conversion
| RBS, muscle mass, abdominal visceral fat*, etc
63
If a target tissue has 5α-reducatse, testosterone will be converted to ____
DHT
64
If a target tissue has aromatase, testosterone will be converted to _____
Estradiol (E2)
65
What are the direct effects of testosterone on target tissues?
Differentiation of epipdidyms, vas deferens, and seminal vesicles (INTERNAL male structures*)
Increased muscle mass
Puberty growth spurt
Growth of seminal vesicles
Deepening of voice
Negative feedback on anterior pituitary
Libido
66
What are the effects of DHT on target tissues?
Differentiation of penis, scrotum and prostate **(EXTERNAL structures)
Male hair pattern
Male pattern baldness
Sebaceous gland activity
Growth of prostate
67
If you lack the ability to turn testosterone into DHT, what kind of genitals will you have
You’ll be male INSIDE, but will have FEMALE external sex organs*********VERY IMPORTATN**
68
Which is more potent: DHT or testosterone
DHT is 2x more potent (androgen receptors are 2x more sensitive)
69
Why is LH and FSH secretion low before puberty/
Hippocampal inhibition of GnRH
70
Why is LH and FSH secretion high during puberty?
Increased GnRH secretion
71
What is senescence?
When a man starts making less testosterone and sperm at an older age (60-80 years)
72
What are some signs of Androgen Deficiency (ADAM)?
Low bone formation
Low muscles
No sex drive
Low body height (compression in spine)
Low hematocrit
Cardiovascular disease
No facial hair
Depression, grumpy, no energy
Change in appetite
73
What are some of the endocrine consequences of exogenous testosterone?
Reduction in LH, FSH via negative feedback
Reduced sperm production-infertility
Increase in free estrogens-exogenous T will free estrogens from binding proteins because it has a greater affinity for the receptors
Increased peripheral conversion of testosterone to estrogens- aromatase has more substrate
74
True or false:
| Supplementing testosterone will actually increase the amount of estrogen in your body
TRUE
Testosterone kicks estrogen off its binding proteins= more free estrogen
Aromatase has more substrate and it makes more estradiol
75
What are some of the risks of testosterone replacement?
Cardiovascular disease (may cause ED) 🍝
Visceral obesity*🐖
Erythrocytosis
Fluid retention🌊
BPH 🌰
Prostate cancer
Acne🍕
Hepatotoxicity🍸
Infertility 😯
Sleep apnea 😴
Gynecomastia and breast cancer 🥥🥥
Psychosis/aggression🤬
Low immunity=cancer
76
What causes pubic and armpit hair to grow
DHEA from the adrenal cortex
77
What causes hair growth in men and is the cause of male pattern hair loss?
DHT
| TOO much of it causes hair loss
78
What is the name of male pattern hair loss
Male androgenetic alone is
79
What kind of hair pattern would you expect to see in castrated males, eunuchoidal patients with androgen-insensitivity syndrome, and those with 5α-reductase definciy
They wouldn’t go bald
80
What causes beard growth?
Synergism between DHT and IGF-1 produced in those cells
81
What causes scalp hair growth to stop
DHT and transforming growth factor β1 (TGF-β1)
82
What causes hair follicles to get tiny
5α-reductase conversion of T to DHT
| Sooo ⬆️5α-reductase on the hair follicle in the presence of TGF-β1= atrophy of hair follicle and stopped hair growth
83
How does Propecia (Finasteride) treat androgenetic alopecia and BPH?
It is a 5α-reductase blocker that prevents the conversion of T to DHT
84
Why should women not even HANDLE Propecia (Finasteride)
If you’re pregnant with a baby boy it could cause external genitalia to develop as female
85
What are some of the side effects of Propecia (finasteride)
ED
Low libido
Reduced ejaculate
86
Where does MOST of the fluid in semen come from?
The seminal vesicles
87
What is in the fluid that seminal vesicles produce?
Fructose to nourish sperm
Prostaglandins to stimulate male and female reproductive tracts (makes sperm motile)
Clotting factors
88
What is in the fluid that the prostate makes?
It is an alkaline fluid to counter the acidic vagina and pH triggers clotting to keep sperm in vagina
FUCKING GROSS 🤮
**********
89
What is the purpose of the fluid produced by the bulboutrethral glands?
Lubricant***
90
Is semen mostly sperm?
No it is 90% fluids from the accessory glands and only 10% sperm
91
Let’s see all the components of semen and where they come from because he said you needed to know it
Testes-sperm and testosterone
Seminal vesicles- fructose to nourish ejaculated sperm, prostaglandins that stimulate motility to help transport the sperm within the male AND female
Prostate- alkaline fluid that neutralizes acidic vaginal secretions
Bulbourethral gland- mucus for lubrication
92
What are some of the problems that the prostate can have
Prostatits- bacterial infection
BPH- enlargement that may affect urination
Cancer- easily treated when caught early
93
Is there a relationship between BPH and prostate cancer?
No
94
Is erection caused by skeletal muscle contraction
No
95
What are the erectile tissues in the penis
2 corpus cavernous a
1 corpus spongiosum
96
What happens in the brain and spinal cord to trigger an erection?
tThe MPOA (medial preoptic area) receives sensory input from the amygdala and sense impulses to the paraventricular nuclei and then the periaqueductal gray matter in the sacral spinal cord (sacral erection generating center). Sacral area sends parasympathetic impulses to the penis.
97
What is the integration site for the CNS control of erections
The MPOA (medial preoptic area)
98
What two things can cause the sacral erection generating center in S2-S4 to start generating parasympathetic impulses to the penis?
Thinking about sex
Mechanical stimulation of the glans
99
What causes the vasodilation of penis arterioles during erection?
Parasympathetic release of NO.
NO activates guanylyl cyclase=cGMP=lower intracellular Ca++= relaxation
100
What keeps the blood in the penis during an erection?
Mechanical compression of veins by SKELETAL muscles at the base of the penis= collapse of venous return from cavernous spaces
101
What causes the bulbourethral glands to make lubricant
Parasympathetic stimulation
102
What happens if the penis receives tonic sympathetic stimulation?
Flaccid penis
103
What would happen if you were to block sympathetic stimulation and stimulate parasympathetic impulses at the same time
Erection in 5 seconds
🌴🦍🐎🥕🍆🍌🦴
104
What keeps guys from having boners all the time?
During the flaccid state, helicine arteries and trabecular smooth muscle are contracted
105
What are the specific arteries that are dilated during erection to cause vasocongestion
Helicine arteries
106
What are the specific veins that get compressed during erection to reduce outflow
Subtunical venules
107
What are the 2 phases of ejaculation?
1. Emission
| 2. Expulsion
108
What happens during Emission?
SNS**** impulses from L1 and L2 cause semen to enter the urethra from contraction of smooth muscle and accessory glands
109
What happens during the Expulsion phase of ejactulation?
Filling of urethra triggers SOMATIC nervous impulses with rhythmic activation of skeletal muscles at the base of the penis
110
What is the pathway of semen during ejaculation
Vas deferens-> ampulla of seminal vesicle -> urethra -> a sock 🧦
111
What keeps semen from backing up into the bladder and pee from coming out during ejaculation?
Internal urethral sphincter contraction
112
What are the 4 phases of orgasm/resolution and which parts are controlled by Parasympathtic vs Sympathttic
1. Excitement- flushed skin, increased muslce tone, hard nipples, erection etc. Parasympathetic
2. Plateu- testicles withdrawn into scrotum. Conditions of excitement phase intensify leading to orgasm. Parasympathtic
3. Orgasm- intense pleasure, expulsion of semen. Involuntary muscle contraction, rhythmic contractions at base of penis result in ejaculation. Heightened emotions, pleasure, HR, perspiration. Sympathetic
4. Resolution- sympathetic vasoconstriction impulses return body to normal function. Blood flow into penis slows. Refractory period.
POINT AND SHOOT
113
What 3 things all need to work together to achieve an erection? (Aka where can things go wrong and cause ED)
Intact central and peripheral nervous system
Corpora cavernous a and spongiosa
Normal arterial blood supply and venous drainage
114
True or false:
| ED can be the first sign of atherosclerosis
True.
Helicine arteries are affected long before heart sx show up
115
What do ED meds do to cause erection
they are PDE5 inhibitors that sustain NO stimulated cGMP levels in the penis
116
When you have a vasectomy, do your testosterone levels decrease/
NO
117
When you have a vasectomy, what happens to all the little sperms being made if they cant get out?!
They are removed through phagocytosis
118
What is it called when you reverse a vasectomy
Vasovasostomy
119
What is vasalgel?
A polymer gel that is injected into each vas deferens, blocking the movement of sperm. Reversible. Currently in human trials.
120
How do synthetic progestins (Desotrogestrel and Etonogestrel) work as male contraception?
They are given in combo with testosterone to produce oligoazoospermia.
Side effects: Acne, weight gain, decreased HDL
Not available in US
121
How does marijuana use affect male fertility?
Marijuana binds to Endocannabinoid receptors in the HPG axis and causes a suppressive effect.
Leads to altered male sex hormones and a neutral or negative effect on fertility.
The endocanabbinoid receptors are also in sperm, and marijuana use can make them unable to move
